JP2011102609A - Electric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric actuator capable of reliably executing the fully-closed or fully-opened operation of a valve in emergency, and reducing facility cost. <P>SOLUTION: The electric actuator includes a control unit 22 and an electric storage device 14. The control unit 22 measures the accumulated energy amount in the electric storage device 14, and determines whether or not the measured accumulated energy amount has the energy amount capable of fully closing or opening a valve from the opening position of the valve based on the opening command value. If the measured accumulated energy does not have the energy capable of fully closing or opening the valve, the valve opening position is controlled while the position for fully closing or opening the valve is defined as the upper limit position in the opening direction or the closing direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric actuator, and more particularly to an electric actuator that is mounted on a rotary valve such as a ball valve or a butterfly valve and that electrically opens and closes the valve body of the valve.

  Conventionally, many electric actuators that control rotation of a rotary valve and the like by electric are used, and this electric actuator rotates an electric motor to rotate an opening / closing shaft of a valve via a gear transmission mechanism. The valve opens and closes.

  In such an electric actuator, for example, in an emergency such as a power failure, it is required to fully close or fully open the valve in order to protect the system. In order to perform the full-close or full-open operation of the valve in an emergency in this way, there is a conventional technique for performing an open / close operation in an emergency using a spring, but there is a problem that noise is generated during an emergency open / close. Have. In addition, there is a problem that a large motor for winding the spring is required.

  Therefore, conventionally, a technology has been disclosed in which a power storage device is mounted to drive an electric motor, and the electric motor is fully closed or fully opened by electric power of the power storage device in an emergency (for example, Patent Literature 1 and Patent Document 2).

JP 2008-089109 A Utility Model Registration No. 3138531

  However, in the conventional technique, when the amount of energy stored in the power storage device is small, such as immediately after the power is turned on, the valve is opened with an opening larger than the opening range that can be operated with the stored energy based on the opening command value. In some cases, the valve cannot be completely closed when the power supply is cut off. This means that it is possible to store energy for shutoff earlier by increasing the charging speed, but it is necessary to set the charging current higher, which increases the cost of the electric actuator and the power supply equipment for the electric actuator. Have the problem of

  The present invention has been made in view of the above points, and an object of the present invention is to provide an electric actuator that can reliably fully close or fully open a valve in an emergency and can reduce equipment costs. It is.

In order to achieve the object, the electric actuator according to the first aspect of the present invention provides an opening corresponding to the opening command value by rotationally driving the electric motor in accordance with the opening command value and the opening position of the valve. A control device that opens and closes the valve;
A power storage device for supplying electric power for rotationally driving the electric motor,
The control device measures the amount of stored energy of the power storage device, and the measured amount of stored energy has an energy amount that can fully close or fully open the valve from the opening position of the valve based on the opening command value. If the amount of energy is not enough to be fully closed or fully opened, the valve opening position is controlled by setting the position where the valve can be fully closed or fully opened as the upper limit position in the opening direction or the closing direction. It is characterized by performing.

  According to a second aspect of the present invention, in the first aspect, the power storage device is an electric double layer capacitor.

  The invention according to claim 3 is characterized in that a control case for housing the control device and the power storage device is detachably provided to a main body that houses the electric motor and to which the valve is mounted.

  According to the first aspect of the present invention, the control device measures the stored energy amount of the power storage device, and the measured stored energy amount is fully closed or fully opened from the valve opening position based on the opening command value. It is determined whether or not it has enough energy, and if it does not have enough energy to fully close or fully open, the position where the valve can be fully closed or fully opened is the upper limit position in the opening direction or closing direction, Since the valve opening position is controlled, the electric motor can be driven by the stored energy of the power storage device in an emergency such as a power failure so that the valve can be fully closed or fully opened. In addition, it is not necessary to increase the current of the power storage device, and the equipment cost can be reduced. In addition, even if the energy storage energy amount of the power storage device does not have enough energy for the valve to be fully closed or fully opened from the opening position based on the opening command value, it is ensured even in the event of an emergency such as a power failure again In addition, it is possible to immediately start valve opening / closing control little by little at the time of power recovery while ensuring a state in which the fully closed or fully open operation is possible, and early recovery of a lifeline such as a water supply facility can be performed.

  According to the second aspect of the present invention, since the power storage device is an electric double layer capacitor, even when the amount of stored energy becomes 0, charge / discharge performance is not deteriorated and efficient power storage is performed. be able to.

  According to the invention of claim 3, since the control case for accommodating the control device and the power storage device is detachably provided to the main body that houses the electric motor and the valve is mounted, the control case is provided in the main body. It is possible to perform control of the present invention by using a conventional electric actuator simply by mounting the device, and the design change of the electric actuator itself becomes unnecessary.

It is sectional drawing which shows embodiment of the electric actuator to which the control apparatus which concerns on this invention is applied. It is a block diagram which shows embodiment of the control apparatus of the electric actuator which concerns on this invention. It is explanatory drawing which shows control in case the fully openable opening degree by the electric actuator which concerns on this invention is smaller than opening degree command value. It is explanatory drawing which shows the state from which the fully openable opening degree by the electric actuator which concerns on this invention becomes large gradually. It is explanatory drawing which shows control when the fully openable opening degree by the electric actuator which concerns on this invention is larger than opening degree command value. It is explanatory drawing which shows control when a valve is forcedly opened by manual operation by the electric actuator which concerns on this invention. It is a flowchart which shows the control action by the electric actuator which concerns on this invention.

  Embodiments of an electric actuator according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of an electric actuator applied to the present invention. An electric actuator 1 according to the present invention is designed to ensure a base 2 and a predetermined space above the base 2. And a cover member 3 that covers the upper surface of the base 2. The base 2 and the cover member 3 constitute a main body 4 of the electric actuator 1. Further, a base plate 5 is installed above the base 2 so as to have a predetermined gap with the base 2, and an electric motor 6 made of, for example, a stepping motor is mounted on the top surface of the base plate 5. Has been. The base 2 is provided with an output shaft (not shown), and a gear transmission (not shown) for transmitting the rotational driving force of the electric motor 6 to the output shaft is provided between the base 2 and the base plate 5. The mechanism is housed.

  A control shaft 7 extending to the upper surface of the cover member 3 is connected to the upper end portion of the output shaft. Below the outer periphery of the control shaft 7, the valve is fully opened by rotating the output shaft and the control shaft 7. Two full-open detection cam members 8 and two full-close detection cam members 9 corresponding to the fully closed positions are attached. Further, on the upper surface of the base plate 5, in the vicinity of the control shaft 7, a full-open position detection switch and a full-close position detection switch comprising micro switches that are turned ON / OFF by a full-open detection cam member 8 and a full-close detection cam member 9. (None of them are shown) are arranged one on top of the other.

  Further, an opening detector 10 (see FIG. 2) is attached in the vicinity of the control shaft 7, and a rotational force is transmitted to the opening detector 10 by a gear attached to the control shaft 7 to open the valve. The degree can be detected. Further, a valve opening indicator 11 having a spherical upper surface is attached to the upper end portion of the control shaft 7, and a viewing window 12 for visually recognizing the opening indicator is formed on the cover member 3. Yes.

  Further, a control case 13 extending upward from the lower surface of the base 2 along the side of the cover member 3 is attached to one lower surface of the base 2, and inside the control case 13, A power storage device 14 made of an electric double layer capacitor is accommodated. Further, a control circuit board 15 is provided below the inside of the control case 13, and a control device 16 is mounted on the control circuit board 15. The control case 13 is formed so as to be detachable with respect to the base 2, and electric parts such as the electric motor 6, the fully open position detection switch and the fully closed position detection switch installed on the base 2, and the control case 13. The control device 16 and the power storage device 14 housed in the battery are electrically connected to perform a predetermined operation. That is, in this embodiment, predetermined control can be performed by attaching the control case 13 to the base 2 of the conventional electric actuator 1.

  A butterfly valve 17 is mounted below the base 2 of the electric actuator 1. The butterfly valve 17 includes a cylindrical body 18, and a stem support portion 19 connected to the lower surface of the electric actuator 1 is integrally formed above the body 18. A stem (not shown) whose upper end is connected to the output shaft of the electric actuator 1 is rotatably inserted into the stem support portion 19. A disk-shaped disc 20 as a connected valve body is rotatably accommodated.

  FIG. 2 is a circuit diagram showing an embodiment of the control device 16 of the electric actuator 1 according to the present invention.

  As shown in FIG. 2, the control device 16 mounted on the control circuit board 15 includes a control unit 22, and the control unit 22 has a motor drive circuit 23 for performing rotational drive control of the electric motor 6. It is connected. A power supply circuit 24 is connected to the control unit 22, and the power supply circuit 24 supplies power for operating the control unit 22 to the control unit 22 and also supplies power for storing power in the power storage device 14. It is configured to supply.

  Further, a valve opening command value SP1 sent from the host side of the control system (not shown) is input to the control unit 22, and the opening detection value PV from the opening detector 10 is the control unit 22. It is comprised so that it may be input.

  In this embodiment, the control unit 22 sends a control signal to the motor drive circuit 23 according to the detected opening value sent from the opening detector 10 based on the opening command value SP1 of the valve sent from the host side. The motor drive circuit 23 controls the rotation drive of the electric motor 6. At this time, in the present embodiment, the control unit 22 measures the amount of stored energy of the power storage device 14, and the measured amount of stored energy of the power storage device 14 is determined from the opening position of the valve based on the opening command value SP1. Determine whether the valve has enough energy to fully close, and if it does not have enough energy to fully close, set the valve opening position as the upper limit of the opening direction. It is comprised so that control may be performed.

That is, if the upper limit value of the opening direction operation that can fully close the valve is the fully-closeable opening LM, this fully-closeable opening LM can be calculated from the stored energy of the capacitor.
Here, the amount of energy stored in the capacitor is
Qc [c] = C [F] × V [V] (1)
Here, Qc is a stored charge, C is a capacitor capacity, and V is a capacitor potential.
Since the charge Qc is proportional to the capacitor potential V, the amount of stored energy can be estimated by measuring the capacitor potential V.

It will be described that the capacitor potential V and the fully openable opening have a proportional relationship.
The valve opening position [°] is determined by the operation time t [second] and the operation speed v [° / second] and is represented by the following equation.
Valve opening position [°] = t [seconds] × v [° / second]
Here, the amount of charge QL required to drive the valve is expressed as follows.
QL [c] = IL [A] × t [seconds]
Here, substituting the relationship between the valve opening and the operating time,
QL [c] = IL [A] × t [second] = IL [A] × valve opening position [°] / v [° / second] (2)

The amount of charge QL required to drive the valve needs to be equal to or less than the amount of charge Qc stored in the power storage device 14. This is because energy is insufficient when Qc is smaller than QL. Considering the loss of power supply, etc., and taking a margin in the amount of power storage, if the margin is α,
Qc [c] = αQL [c]
Therefore, substituting equation (1) for the left side and equation (2) for the left side,
C [F] × V [V] = (α × IL [A] × valve opening position [°]) / v [° / second]
V [V] = (α × IL [A] × valve opening position [°]) / (v [° / second] × C [F])

Where α, IL, v, and C are constants,
If β = (α × IL [A]) / (v [° / second] × C [F]),
V [V] = β × valve opening position [°]
Thus, it can be said that the capacitor potential V is proportional to the valve opening.
If the valve opening at this time is defined as fully openable opening LM,
V [V] = β × LM

Therefore, the fully-closeable opening LM is
Fully closeable opening LM [°] = capacitor potential V [°] / β
It can be said that the capacitor potential, that is, the stored energy amount QC, and the fully-closeable opening degree LM are in a proportional relationship.

  By measuring the amount of stored energy in this way, the fully-closeable opening can be calculated, and this is used to perform opening control according to the amount of stored energy.

  Specifically, for example, as shown in FIG. 3, when the fully-closeable opening degree LM calculated from the stored energy amount of the power storage device 14 is 30% with respect to the opening degree command value of 60%, the valve opening degree Regardless of the opening command value SP1, the opening is opened up to 30%. In this case, the opening command value SP1 is opened with a small opening, but it is possible to flow a fluid. For example, even when an emergency shutoff is performed due to a power failure or the like, Fully closed is possible. Then, as shown in FIG. 4, when the power storage device 14 resumes energization from the power supply source, the amount of stored energy gradually increases. Therefore, the fully-closeable opening degree LM is gradually increased as the amount of stored energy increases, and the valve opening degree is controlled to increase in accordance with the fully-closeable opening degree LM. At this time, the charging speed is slower than the valve operating speed, and the fully-closeable opening LM is calculated by the sampled capacitor potential. Therefore, the valve opening operating speed is intermittent according to the sampling interval of the capacitor potential. Inching operation is performed.

  When the opening command value SP1 is smaller than the fully-closeable opening LM, as shown in FIG. 5, valve opening control is performed according to the opening command value SP1. As an exception, there is a case where the valve is forcibly opened by manual operation after an emergency shutdown. In this case, when power is restored, the valve can be fully closed from the opening position of the manual operation as shown in FIG. The closing operation is performed up to the opening LM.

  Here, when the electric motor 6 is driven, a constant voltage is required. On the other hand, since the voltage of the electric double layer capacitor drops as much as energy is consumed, the capacitor alone cannot be used as a constant voltage source. Therefore, when the electric motor 6 is driven by the power storage device 14, the electric motor 6 is driven at a constant voltage value via a constant voltage circuit provided in the power supply circuit 24. In order to make the voltage value constant by the constant voltage circuit, it is difficult to use until the amount of energy stored in the power storage device 14 becomes 0 volts. Therefore, in the present embodiment, it is preferable to calculate the stored energy amount for calculating the fully-closeable opening degree in consideration of this. Moreover, in the above-mentioned case, an example in which an electric double layer capacitor is used as the power storage device 14 is shown, and even when the amount of stored energy becomes 0, the charge / discharge performance does not deteriorate. When a lithium ion capacitor is used as the power storage device 14, if the voltage value of the power storage device 14 falls below a specific lower limit voltage, a constant voltage cannot be obtained. There is a problem that will decrease. In particular, bulbs installed as building equipment are often installed in buildings under construction, and there are cases where power is not supplied for a long time after the bulb is installed. May be less than Therefore, when using a lithium ion capacitor as the power storage device 14, it is preferable to use a dry battery and a booster circuit so as not to fall below the lower limit voltage.

  Next, the operation of the electric actuator 1 according to the present invention will be described with reference to the flowchart shown in FIG.

  First, the control unit 22 measures the amount of stored energy of the power storage device 14 (ST1), and calculates the time during which the valve can operate based on the amount of stored energy (ST2). Based on the valve operable time, a fully-closeable opening LM that can be operated until fully closed is calculated (ST3). Then, the opening command value SP1 and the current valve opening PV are detected (ST4), and the opening command value SP1 and the fully openable opening LM are compared (ST5).

  If the fully-closeable opening LM is equal to or less than the opening command value SP1, the fully-closeable opening LM is replaced with the opening command value SP2 (ST6). On the other hand, if the fully-closeable opening LM is larger than the opening command value SP1, the opening command value SP1 is replaced with the opening command value SP2 (ST7). Then, the opening command value SP2 is compared with the current valve opening PV (ST8), and when the opening command value SP2 is smaller than the current valve opening PV, the valve is closed (ST9). When the opening command value SP2 is larger than the current valve opening PV, the valve is opened (ST10). Further, when the opening command value SP2 is equal to the current valve opening PV, the operation of the valve is stopped (ST11). The above operation is repeated until the power supply is cut off, such as in an emergency.

  As described above, in the present embodiment, it is determined whether or not the amount of energy stored in the power storage device 14 has sufficient energy to fully close the valve from the valve opening position based on the opening command value. When the valve does not have enough energy to be fully closed, the valve opening position is controlled with the position where the valve can be fully closed as the upper limit of the opening direction. The electric motor 6 can be driven by the stored energy of 14, and the valve can be reliably fully closed. In addition, it is not necessary to increase the current of the power storage device 14 and the equipment cost can be reduced. Moreover, the control of the present invention can be performed by using the conventional electric actuator 1 only by attaching the control case 13 to the main body 4, and the design change of the electric actuator 1 itself becomes unnecessary. In addition, even if the energy storage energy amount of the power storage device does not have an energy amount that allows the valve to be fully closed from the opening position based on the opening command value, it is ensured that the energy storage device will be fully protected in the event of an emergency such as a power failure. While ensuring a state in which the closing operation is possible, when the power is restored, the valve opening / closing control can be immediately started little by little, and the lifeline such as the water supply facility can be restored early.

  In the above embodiment, the case where the opening command value is sent from the host side of the control system has been described. However, based on the program stored in the control device 16 of the electric actuator 1, the valve opening detection value is set. In response to this, it may be sent from a so-called autonomous system that automatically assigns the opening command value. In addition to the case where the valve opening degree detection value is sent from the valve opening degree detector, the valve opening degree detection value is given in the control device 16 of the electric actuator according to the absolute rotational position of the electric motor 6 like a stepping motor. It may be. Furthermore, when determining the amount of energy stored in the power storage device 14, the determination may be based on a data table stored in advance, in addition to the determination based on the above-described calculation formula.

  The present invention can also be applied to other valves such as a lift valve such as a gate valve and a needle valve in addition to a rotary valve such as a ball valve and a butterfly valve.

  Moreover, in the said embodiment, although the control in the case of making a valve fully close in emergency was demonstrated, it is also applicable to the control in the case of making a valve fully open in the case of emergency. That is, when the valve is fully closed, for example, it is suitable for driving a valve used in equipment for air conditioning, hot water supply, and water supply, and when the valve is fully opened, it is suitable for fire equipment such as a sprinkler. This is suitable for driving a valve to be used.

  The present invention is not limited to the above-described embodiment, and various modifications can be made based on the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Base 3 Cover member 4 Main body 5 Ground plate 6 Electric motor 7 Control shaft 10 Opening detector 13 Control case 14 Power storage device 15 Control circuit board 16 Control device 17 Butterfly valve 18 Body 20 Disc 22 Control part 23 Motor drive Circuit 24 Power supply circuit

Claims (3)

A control device that rotationally drives the electric motor according to the opening command value and the opening position of the valve to control opening and closing of the valve to an opening corresponding to the opening command value;
A power storage device for supplying electric power for rotationally driving the electric motor,
The control device measures the amount of stored energy of the power storage device, and the measured amount of stored energy has an energy amount that can fully close or fully open the valve from the opening position of the valve based on the opening command value. If the amount of energy is not enough to be fully closed or fully opened, the valve opening position is controlled by setting the position where the valve can be fully closed or fully opened as the upper limit position in the opening direction or the closing direction. The electric actuator characterized by performing.   The electric actuator according to claim 1, wherein the power storage device is an electric double layer capacitor.   The control case for accommodating the control device and the power storage device is detachably provided to a main body that houses the electric motor and the valve is mounted. Electric actuator.

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